From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit fc9fd3f98423367c79e0bd85a9515df26dc1b3cc ]
write_ibpb() does IBPB, which (among other things) flushes branch type predictions on AMD. If the CPU has SRSO_NO, or if the SRSO mitigation has been disabled, branch type flushing isn't needed, in which case the lighter-weight SBPB can be used.
The 'x86_pred_cmd' variable already keeps track of whether IBPB or SBPB should be used. Use that instead of hardcoding IBPB.
Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Link: https://lore.kernel.org/r/17c5dcd14b29199b75199d67ff7758de9d9a4928.174414825... Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/entry/entry.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S index b7ea3e8e9eccd..58e3124ee2b42 100644 --- a/arch/x86/entry/entry.S +++ b/arch/x86/entry/entry.S @@ -18,7 +18,7 @@
SYM_FUNC_START(entry_ibpb) movl $MSR_IA32_PRED_CMD, %ecx - movl $PRED_CMD_IBPB, %eax + movl _ASM_RIP(x86_pred_cmd), %eax xorl %edx, %edx wrmsr